When people suffer from some types of heart arrhythmias, the result may be that blood flow to various parts of the body is reduced. Some arrhythmias may even result in a Sudden Cardiac Arrest (SCA). SCA can lead to death very quickly, e.g. within 10 minutes, unless treated in the interim.
Some people have an increased risk of SCA. People at a higher risk include individuals who have had a heart attack, or a prior SCA episode. A frequent recommendation is for these people to receive an Implantable Cardioverter Defibrillator (“ICD”). The ICD is surgically implanted in the chest, and continuously monitors the person's electrocardiogram (“ECG”). If certain types of heart arrhythmias are detected, then the ICD delivers an electric shock through the heart.
After being identified as having an increased risk of an SCA, and before receiving an ICD, these people are sometimes given a Wearable Cardiac Defibrillator (“WCD”) system. A WCD system typically includes a harness, vest, or other garment that is configured to be worn by the patient. The WCD system includes a defibrillator and external electrodes, which are attached to the inside of the harness, vest, or other garment. When the patient wears the WCD system, the external electrodes can help monitor the patient's ECG. If a shockable heart arrhythmia is detected, then the defibrillator of the WCD system delivers the appropriate electric shock through the patient's body, and thus through the heart.
A challenge in the prior art remains with the monitoring electrodes. Electrodes may need to make good electrical contact with the patient's skin, without being intrusive or irritating the skin.